[Community structure of zooxanthellate corals (Anthozoa: Scleractinia) in Carrizales coral reef, Pacific coast, Mexico]. / Estructura comunitaria de corales zooxantelados (Anthozoa: Scleractinia) en el arrecife coralino de Carrizales, Pacifico Mexicano.

Coral reefs in the Mexican Pacific and notably those of the continental coastline of Colima state are still poorly studied. Fortunately, recent efforts have been carried out by researchers from different Mexican institutions to fill up these information gaps. The aim of this study was to determine the ecological structure of the rich and undisturbed coral building communities of Carrizales by using the point transect interception method (25m-long). For this, three survey expeditions were conducted between June and October 2005 and September 2006; and for comparison purposes, the reef was subdivided according to its position in the bay, and depth (0 to 5 m, and 6 to 10 m). Thirteen coral species were observed in the area, with Pocillopora verrucosa as the most abundant, contributing up to 32.8% of total cover, followed by Porites panamensis and Pocillopora capitata with 11% and 7%, respectively. Other species, Pocillopora damicornis, Pavona gigantea, Pocillopora eydouxi and Pocillopora inflata accounted for 1.5% to 2% of coral cover whereas the remaining five species had cover of less than 1%. Seven of the observed species represented new records for Colima state coastline: Pocillopora eydouxi, P inflata, P meandrina, Pavona duerdeni, P varians, Psammocora stellata and P contigua. This last species is a relevant record, because it has never been observed before in the Eastern Pacific. Although there was no significant difference (ANOVA, p = 0.478) neither in the abundance between the sides of the bay, nor between the depths considered, and the shallow zone observed the higher coral cover. Live coral cover was up to 61%, one of the highest ever reported for the Mexican Pacific, including the Gulf of California. The observed values of diversity (H' = 0.44 +/- 0.02), uniformity (J' = 0.76 +/- 0.02), and taxonomic distinctness index (delta* = 45.87 +/- 3.16), showed that currently this is the most important coral reef of Colima coastline. Currently, this region does not show any disturbance effects, but the increasing economic development of Manzanillo, as one of the main commercial ports of Mexico, its proximity to the reef, and the burgeoning number of tourists, may have some ecosystem impacts, for which management and conservation plans for Colima coastline are highly recommended.

Host-symbiont recombination versus natural selection in the response of coral-dinoflagellate symbioses to environmental disturbance.

Mutualisms between reef-building corals and endosymbiotic dinoflagellates are particularly sensitive to environmental stress, yet the ecosystems they construct have endured major oscillations in global climate. During the winter of 2008, an extreme cold-water event occurred in the Gulf of California that bleached corals in the genus Pocillopora harbouring a thermally 'sensitive' symbiont, designated Symbiodinium C1b-c, while colonies possessing Symbiodinium D1 were mostly unaffected. Certain bleached colonies recovered quickly while others suffered partial or complete mortality. In most colonies, no appreciable change was observed in the identity of the original symbiont, indicating that these partnerships are stable. During the initial phases of recovery, a third species of symbiont B1(Aiptasia), genetically identical to that harboured by the invasive anemone, Aiptasia sp., grew opportunistically and was visible as light-yellow patches on the branch tips of several colonies. However, this symbiont did not persist and was displaced in all cases by C1b-c several months later. Colonies with D1 were abundant at inshore habitats along the continental eastern Pacific, where seasonal turbidity is high relative to offshore islands. Environmental conditions of the central and southern coasts of Mexico were not sufficient to explain the exclusivity of D1 Pocillopora in these regions. It is possible that mass mortalities associated with major thermal disturbances during the 1997-1998 El Niño Southern Oscillation eliminated C1b-c holobionts from these locations. The differential loss of Pocillopora holobionts in response to thermal stress suggests that natural selection on existing variation can cause rapid and significant shifts in the frequency of particular coral-algal partnerships. However, coral populations may take decades to recover following episodes of severe selection, thereby raising considerable uncertainty about the long-term viability of these communities.

The putative endemic Mexican reef coral Porites baueri Squires 1959 (Scleractinia: Poritidae) is a synonym of the widespread coral Porites lobata Dana 1846.

Morphological analysis and microscopic observations of the Porites baueri holotype and specimens of other Porites species from different sites of the Mexican Pacific, allowed confirmation that Porites baueri is subjective synonym of Porites lobata. The holotype of Porites baueri was collected in the Marías Islands in 1957, and described as a new species by Squires in 1959. Since then, this species was considered as endemic, which is due to the lack of other specimens or a review of the taxonomic characters until now. The Mexican Pacific marine fauna loses a valid reef coral species, currently at 34, but gains in taxonomic clarity by ending almost 60 years of controversy.

Agregación masiva de la estrella de mar Luidia bellonae (Paxillosida: Luidiidae) en Bahía de Banderas, Jalisco, Pacífico Mexicano / Massive aggregation of sea star Luidia bellonae (Paxillosida: Luidiidae) in Bahía de Banderas, Jalisco, Mexican Pacific

Resumen Introducción: En el Pacífico central mexicano son escasos los trabajos sobre ecología de asteroideos. Estas especies generalmente se distribuyen de forma aleatoria, aunque en algunas ocasiones pueden encontrarse en grupos o agregaciones. En Los Arcos, al sur de Puerto Vallarta, en Bahía de Banderas, México, se observó Luidia bellonae por primera vez en una agregación masiva en 2021. Objetivo: Reportar por primera vez el registro de esta especie en esta región del Pacífico mexicano, así como el evento de agregación masiva. Métodos: Se realizaron transectos y recorridos para cuantificar la densidad y medir los ejemplares de la estrella en Los Arcos, Bahía de Banderas, durante 2021, 2022 y 2023. Resultados: Se encontraron densidades promedio de 2.65 ind/m2 y hasta 7 ind/m2. En total en el área aproximada de 900 m2 se registraron 630 individuos. Los ejemplares midieron (R) entre 2 y 12 cm, y en su mayoría midieron entre 4 y 8 cm. Conclusiones: L. bellonae estaba reportada en distintos sitios en algunos estados del Pacífico mexicano, sin embargo no estaba registrada para Bahía de Banderas ni Los Arcos, ni tampoco en la cantidad que se reporta aquí, por lo que este es el primer registro para la especie con una presencia masiva para el Pacífico mexicano. La aparición de la gran cantidad de ejemplares de L. bellonae en Los Arcos en 2021 pudo haber sido resultado de una combinación de factores, entre ellos la baja temperatura del agua, con valores hasta de 15 ºC y la alta cantidad de nutrientes. Este hallazgo demuestra la necesidad de más estudios sobre los equinodermos y especies marinas para entender la influencia que tienen las condiciones ambientales en su ciclo de vida.

Abstract Introduction: In the central Mexican Pacific, there are few studies on asteroid ecology. These species are generally distributed randomly, although in some cases groups or aggregations can be found. In Los Arcos, south of Puerto Vallarta, in Bahía de Banderas, Mexico, Luidia bellonae was observed for the first time in a massive aggregation in 2021. Objective: To report the new record of this species in this region of the Mexican Pacific and its massive aggregation event. Methods: Transects and surveys were carried out to quantify the density and measure the sea star individuals in Los Arcos, Bahía de Banderas during 2021, 2022, and 2023. Results: Average densities of 2.65 ind/m2 and up to 7 ind/m2 were found. In total, in the approximate area of 900 m2, 630 individuals were registered. The specimens measured (R) between 2 and 12 cm, and most measured between 4 and 8 cm. Conclusions: L. bellonae has been reported in different places in some states of the Mexican Pacific; however, it was not registered for Bahía de Banderas nor Los Arcos, nor in the amount reported here, therefore this is the first record for the species with a massive presence for the Mexican Pacific. The appearance of the large number of L. bellonae specimens in Los Arcos in 2021 could have been the result of a combination of factors, including the low water temperature, with values up to 15 ºC, and the high amount of nutrients. This finding demonstrates the need for more studies on echinoderms and marine species to understand the influence of environmental conditions on their life cycle.

Estructura comunitaria de corales zooxantelados (Anthozoa: Scleractinia) en el arrecife coralino de Carrizales, Pacífico Mexicano / Community structure of zooxanthellate corals (Anthozoa: Scleractinia) in Carrizales coral reef, Pacific coast, Mexico

Coral reefs in the Mexican Pacific and notably those of the continental coastline of Colima state are still poorly studied. Fortunately, recent efforts have been carried out by researchers from different Mexican institutions to fill up these information gaps. The aim of this study was to determine the ecological structure of the rich and undisturbed coral building communities of Carrizales by using the point transect interception method (25m-long). For this, three survey expeditions were conducted between June and October 2005 and September 2006; and for comparison purposes, the reef was subdivided according to its position in the bay, and depth (0 to 5m, and 6 to 10m). Thirteen coral species were observed in the area, with Pocillopora verrucosa as the most abundant, contributing up to 32.8% of total cover, followed by Porites panamensis and Pocillopora capitata with 11% and 7%, respectively. Other species, Pocillopora damicornis, Pavona gigantea, Pocillopora eydouxi and Pocillopora inflata accounted for 1.5% to 2% of coral cover whereas the remaining five species had cover of less than 1%. Seven of the observed species represented new records for Colima state coast- line: Pocillopora eydouxi, P. inflata, P. meandrina, Pavona duerdeni, P. varians, Psammocora stellata and P. contigua. This last species is a relevant record, because it has never been observed before in the Eastern Pacific. Although there was no significant difference (ANOVA, p=0.478) neither in the abundance between the sides of the bay, nor between the depths considered, and the shallow zone observed the higher coral cover. Live coral cover was up to 61%, one of the highest ever reported for the Mexican Pacific, including the Gulf of California. The observed values of diversity (H´=0.44±0.02), uniformity (J´=0.76±0.02), and taxonomic distinctness index (Δ*=45.87±3.16), showed that currently this is the most important coral reef of Colima coastline. Currently, this region does not show any disturbance effects, but the increasing economic development of Manzanillo, as one of the main commercial ports of Mexico, its proximity to the reef, and the burgeoning number of tourists, may have some ecosystem impacts, for which management and conservation plans for Colima coastline are highly recommended.

El conocimiento ecológico de corales arrecifales en el Pacífico mexicano es escaso, por lo que el objetivo de este trabajo fue determinar la estructura de la comunidad de corales hermatípicos en el arrecife de Carrizales, Colima, mediante el uso de transectos y buceo autónomo (junio y octubre 2005, septiembre 2006). De las 13 especies de corales encontradas, Pocillopora verrucosa fue la más abundante y siete representan nuevos registros, sobresaliendo Psammocora contigua, primer registro para el Pacífico Oriental. No hubo diferencias significativas de abundancia entre profundidades, pero la zona somera presenta una mayor cobertura. Este sitio presenta una de las riquezas y cobertura de coral más alta (61%) en el Pacífico Mexicano y valores de diversidad (H´=0.44±0.02), uniformidad (J´=0.76±0.02), y de diferenciación taxonómica (Δ*=45.87±3.16) relativamente altos. Actualmente la región no presenta grandes perturbaciones pero el creciente desarrollo económico de Manzanillo, uno de los principales puertos comerciales del país, además del creciente número de turistas, podrían afectar al arrecife, por lo que se sugiere implementar medidas de protección con el fin de mantener al arrecife más importante del litoral de Colima.